The present invention concerns MacPherson type suspension shock struts. Said shock struts contain a jack and a spring surrounding the jack. The jack secures a transverse guidance maintaining the wheel carrier and generally contains a shock absorber. The invention concerns, notably, the coupling attachments which constitute a filtering and connecting part ensuring anchorage of the upper part of the MacPherson shock struts on the body and which, if necessary, further provide a support for the spring. When shock struts for driving wheels are involved, a ball bearing ensures the necessary degree of rotation freedom between the wheel carrier and the body support surface.
Said coupling attachments contain a filtering and uncoupling articulation, called elastic articulation here, on the path transmitting the spring efforts to the body. That separate elastic block makes possible a filtering independent of the efforts transmitted by the spring and affords greater comfort. Or else the path transmitting the spring efforts to the body also passes through the elastic articulation. Numerous variations of such coupling attachments exist. This invention relates only to shock struts in which the efforts transmitted by the shock absorber rod passes through the elastic articulations and in which the load of the vehicles does not pass through said elastic articulation.
The object of the invention is to improve the compactness of the shock struts and more specifically the compactness of the assembly localized in the upper part of the shock strut, in order to leave free rein to stylists who want to design ever more plunging hoods.
It is, in fact, advantageous to have the least possible stresses as to the size of the suspensions. Another object of the invention is to reduce the cost of such coupling attachments, without impairing their quality of filtering the vibrations appearing when the vehicle is running over a road. That filtering is very important for passenger comfort.
The invention concerns an upper coupling attachment for a MacPherson vehicle suspension, comprising:
a mounting bearing for mounting on a vehicle body;
a support bearing and a centering bearing for engaging a ring transmitting a static load supported by the suspension, said support bearing and said centering bearing defining a housing for mounting the ring;
a center opening designed for receiving a rod of a shock strut having a body and a rod sliding in the body, said center opening determining the position of a shaft on which the body turns in relation to the rod;
a center reinforcement having said center opening on one side and a flange on the other side;
an outer reinforcement having said mounting bearing on one side and containing a flange surrounding a center hole;
an elastic block adhered to said outer reinforcement on the side opposite said mounting bearing, said elastic block having said support bearing for the ring;
an elastic articulation of elastomeric material, adhered to an anchoring surface machined on said outer reinforcement on one side and adhered to an anchoring surface 311 machined on said center reinforcement on the other side.
According to one aspect of the invention, said coupling attachment is such that:
said center reinforcement and said outer reinforcement are so shaped relative to each other that said center reinforcement does not pass through said center hole;
said center reinforcement and said outer reinforcement are so positioned in relation to each other that said outer reinforcement at least partially surrounds said center reinforcement such that said anchoring surfaces are partially superposed radially and axially displaced;
said support bearing and said centering bearing for the ring lying axially between said mounting bearing and said flange.
According to another aspect of the invention, said coupling attachment is such that said elastic block is made of an elastomeric material devoid of any metal reinforcement between the mounting bearing and the ball bearing support.
According to another aspect of the invention, said coupling attachment is such that
said center reinforcement and said outer reinforcement are so positioned in relation to each other that said outer reinforcement at least partially surrounds said center reinforcement such that said anchoring surfaces are partially superposed radially and axially displaced;
said center reinforcement contains a roughly truncated cone-shaped side wall developing on the side of said center opening opposite the side receiving the shock strut, the vertex of the virtual cone being situated on the side of said center opening receiving the shock strut, said side wall having a maximum diameter "PHgr"M, wherein the radially outer surface of said side wall contains said anchoring surface of said elastic articulation,
said outer reinforcement contains an upper flange incorporating said mounting bearing on the body, said flange being extended by a roughly truncated cone-shaped side wall containing said anchoring surface of said elastic articulation, wherein said roughly truncated cone-shaped side wall containing said anchoring surface of said elastic articulation extends axially from the opposite side to said mounting bearing and has a minimum diameter "PHgr"m that is strictly less than "PHgr"M.
It is with reference to the axis defined by the center opening that the axial direction (parallel to the axis) and radial direction (perpendicular to the axis) are defined. The center opening defines perfectly geometrically the mounting of the shock strut on the coupling attachment, for that is an area whereby one of the reinforcements is supported on the shock strut rod; there is no degree of freedom between the rod and said reinforcement.
The proposed coupling attachment fulfills the articulation functions allowing movements of the shock strut around the axis of deflection when the coupling attachment is used for a driving wheel. In all the uses, it fulfills the functions of filtering the spring through the elastic block and of filtering the shock absorber through the articulation. It is known that this type of suspension generally contains a so-called shock pad; this is an elastomer pad that the body of the shock absorber strikes when the suspension comes to a clearance stop. In that case, the suspension includes a bowl mounted on the rod and at least partially containing a shock pad concentric to the shock strut, said bowl being in contact with said center opening of said center reinforcement, and said bowl containing a support surface in the axial extension of the flange of the outer reinforcement.
The invention makes it possible to pass the load transmitted to the body by the shock pad without going through either the articulation or the ball bearing in case of use on driving wheels.
In fact, shocks, even when filtered by the shock pad, are harmful to the stability of the ball bearing, and the elastic articulation of this type of coupling attachment is not designed to take up heavy loads, for the spring load does not pass through said articulation.
The housing that the invention makes it possible to arrange enables the first turn of the spring and, if necessary, the ball bearing to be placed roughly in the same plane perpendicular to the axis as said articulation. According to that aspect of the invention, the suspension contains a spring, the first turn of which comes axially between the mounting bearing and the flange of the outer reinforcement, or else, in the case of driving wheels, contains a spring and a ball bearing, one of the races of which constitutes the said ring or is supported on said ring, the ball bearing coming axially between the mounting bearing and the flange, and the other race turning with the spring to follow the direction of the driving wheels.
The invention makes it possible to reduce the number of components of the upper anchorage of the shock strut on the body of the vehicle. It makes it possible to install a very high ball bearing, at the same height as the elastic articulation. Thus, the ball bearing does not result in any extra thickness in relation to the coupling attachment itself. The height of the coupling attachment is dictated only by the proportions of the elastic articulation ensuring uncoupling between the rod of the shock strut jack and the body of the vehicles, as well as the filtering ensuring, notably, better acoustic comfort.
The invention will be better understood from the description of nonlimiting examples. For example, a nonlimiting characteristic of these examples resides in the fact that the second race of the ball bearing is supported each time on an elastic block integral with said outer reinforcement.